There has been considerable activity to control the use of water. Every means has been explored with regard to reducing wastage. For instance steps have been taken to reduce the quantity of water being introduced into a toilet bowl in order to fill the bowl to at least the U-trap level. It is necessary to have at least that much water in the toilet bowl so that noxious fumes cannot flow back from a sewer system. This control of water flow has been affected by reducing the flow stream volume to the overflow tube that connects to the toilet bowl.
In other words, the tube to the overflow tube carries water as long as the valve is open that is controlled by the float whereby as water flows into the water closet tank refill water is entering the overflow tube and is thereby refilling the tank bowl. By slowing the stream to the overflow tube during the water closet refill cycle less water is distributed into the overflow tube and hence to the toilet bowl itself.
In U.S. Pat. No. 4,145,775 to Butler considerable progress has been made in controlling the fluid volume into the overflow tube. This patent is incorporated herein by reference in its entirety.